Offset clamping connector



May 25, 1948. M. THOMAS OFFSET CLAMPING CONNECTOR Filed July 7, 1947 Fl-G.

FIG. 2.

FIG. 4,

FIG. 3.

INVENTOR MICHAEL THOMAS ATTORNEY Patented May 25, 1948 UNlTED OFFSET GLAMPING CONNECTOR Michael .Thomas, Los Angeles, Calif., assignor to T 8; M Manufacturing Company, LosfAngeles, Calif., a firm composed of Michael Thomas and J. J. Masterson Application July 7, 1947, Serial No. 759,323

3 Claims. (01. 235-5) 7 This invention relates to improvements in clamping connectors for sheet metal boxes used in electrical service wiring such as switch boxes, gutters, and the like.

One object of the invention is to provide a supporting connector formetal boxes used in electrical service wiring which also serves as a conduit for. the electric wiring. Another object is to provide a clamping conduit connector which is readily adaptable for joining boxes having outof-register knock-out holes. A further object is to provide a clamping connector which may be applied to align the faces of the boxes with the adjoining wall,

These and other objects are attained by my invention which will be understood from the following description and the accompanying drawings in' which:

Fig. 1 is a side elevational view showing my offset clamping connector as used to hold together the adjoining walls of a switch box and a gutter box;

Fig. 2 is an end elevational view of the offset connector;

Fig. 3 is a diagrammatic view showing how my offset connector may be used to align switch boxes having knock-out holes at non-uniform distances from the edges;

Fig. 4 is a cross-sectional view of a switch box and a gutter box with knock-out holes out of alignment, jointed together and aligned at the faces by one of my offset connectors.

In connection with electric wiring practices, it is often desirable to use two or more metal cabinet boxes positioned close together, and to connect these two boxes with each other mechanically by means which will form a conduit through which electrical conductors or wires may pass from one box to the other. It has been common practice to use externally threaded pipe nipples and nuts, or internally threaded bushings to connect two boxes together in this manner. These require not only more expensive parts, but also require much more time to properly install, and the arrangement is mechanically not very rigid, and as ordinarily applied, the electrical connection between the parts is not good enough to provide a satisfactory grounding circuit. The knock-out holes in the boxes, into which connectors are inserted, are not always provided at standard distances from the walls, and hence the faces of the boxes cannot be properly aligned with the wall or panel faces. My offset clamping connector solves the problem not only of providing a readily assembled connector and support for one box upon another, but also permits easy alignment of the box faces to conform to the wall face into which the box is to be set.

Referring to the drawings, my connector device consists of a'tubular body'portion H having a flange I2 at one end, and external threads l3 at the other end, the portion between the flange and the threads being axially offset. The axis of the flange l2 and the axis of the portion having the threads I3 may be displaced as far as desired, although practically I have found that a displace ment of about half the diameter of the tube is most useful. A tubular spacer I4 is provided, the internal diameter of which is great enough to encompass the offset portion of the body I I, leaving the ends of the spacer parallel to the flange in order to press against the sheet metal of one box being connected; and a nut l5 adapted to be threaded on the threads I3 is also provided. The device is adapted to be put through knock-out holes in sheet metal boxes, and the diameter of the off-set portion of the body must be kept small enough to permit putting it through a standard knock-out hole. The sheet metal around a knockout hole of one box is clamped between the underside of the flange l2 and one end of the tubular spacer l4, and the sheet metal around the knockout hole of another box is clamped between the other end of the spacer l4 and the face of the nut l5. When parts are in place, the faces of the boxes are aligned as desired by rotating the off-set body, and then tighten-ing the nut 15 to clamp the parts together, holding the body in the selected axial position by means of the ears on the flange.

In placing electrical fixture boxes and the like, it is usually not important if they are shifted parallel to the wall along which they are being placed, providing the faces are flush with the surface wall or panel. Therefore, if the knockout holes happen to be provided in the boxes at even distances from the face of the boxes,- my off-set clamping connector may be used, although the off-set is not required. It is, therefore, not necessary to carry both off-set and straight connectors in stock.

In Fig. 3 is shown, diagrammatically, illustrative arrangements of knock-out holes in adjoining boxes to which my off-set clamping connector may be advantageously applied so that the faces of all of the boxes, may be aligned with a wall face. Fig. 4 shows one arrangement in detail.

By means of the ears on the flange of the bushing, the assembly of the two boxes may be easily 1 selected to meet trade conditions.

In other types of connectors between boxes, .it.v

frequently requires two workmen, because one man cannot see to manipulate-ithe triecessaryrji tools simultaneously in the two boxes.

My device is simple andinexrngrrsivezt mannai facture and to install. 'I'he vparts imaygof-conrse,g

be made of any suitable length and diameter to meet the requirements for standard electrical wiring fixtures and the amount aof-fifisetmay be preferably made of stock so selected that the mechanical connections between boxes will be strong and rigid.

Iwilaim: r p 1. A clamping connector -'for mechanically The parts (are joining electrical switch-boxes 'and the -"like --and or for providing EeIec'triCa-I 'wi-ring 'conduits therebetween, consisting of a tubular body having an outwardly extending flange at one end and external'threads at the other end, the said flange having spaced ears adapted for hand gripping, the tubular central portion of said body between .saidrflange andsaid sleeue beingiaxially ofiset; :a spacer adapted to fltiroverttlre ecferrtral ofiset portion of said body; and a'lokin'g 'nut adapted ,to screw ontothe threads of said body. 7

'2. A clamping connector comprising a tubular body Ehaxiing outside flange at one end and external threads at the other, the tubular cent tral;portiorifofrsaidibody being offset so that'the .1;axisgrifjtheifiange;lies to one side of the axis of the thiieadedjpgrtion and parallel thereto; and a locking nut adapted to screw onto the threaded ortion ofsairl body.

"3. A ..body for a clamping connector for use in joining sheet metal boxes and the like consisting of an axially ofi -set cylindrical metal sleeve having an' outwardly extending'fflange at one end and external threads at the other *endthe {said flange having spa'cedperipherakears,

MICHAEL 

